Water Inside Wall Cavities
Wall cavities can harbor mold growth. Mold growth is fostered by water intrusion providing one of the necessary elements required to support mold. Appropriate temperature and the organic materials inside the wall cavity supply the additional ingredients. There are numerous ways that water can find its way into these spaces, but often there are few indications of building materials inside the wall becoming wet enough to harbor stealth contamination.
Knowing what to look for and actually looking closely can be your main tools for determining if you have a hidden mold problem. There are some situations, such as a very slow or intermittent plumbing leak or irrigation water impacting on an exterior wall, that there are little or no obvious visual indications at all.
The places to look for indications of water intrusion are all perimeter walls where water from irrigation or pooling from rain run-off or water through the slab from a high water table could enter. Even slight water stains on an exterior wall could be a sign that sprinkler water impacts on the wall. You can observe the sprinkler operating to determine if that is the case. If you live in a windy area see what happens when the wind is blowing toward the wall.
Perimeter walls in most houses built from around the late 1950’s to the present are constructed of drywall with fiberglass insulation inside the cavities. Drywall paper is easily digestible food for many molds and the insulation is an enabler. The fiberglass serves as a sponge, soaking up water and holding it inside the wall cavity for relatively long periods of time rather than allowing it to run out at the bottom of the wall. The conditions for mold growth are provided for a sufficient amount of time to allow significant mold contamination.
Walls in close proximity to plumbing fixtures should always be checked. Small leaks especially from pinhole penetrations in copper pipes can cause water leaks that are minimal enough to show little or no indication for a considerable period of time. This is especially the case with a small leak from a shower deflector. Water only passes through that pipe when the shower is in use, so the leak is very intermittent and results in water intrusion sufficient for mold growth but with no visual indications.
Ceiling leaks, either from a compromised roof or from an upper floor plumbing leak will usually be detected by water stains on the ceiling. Often if the leak is quickly repaired, the stained ceiling is painted over or a small portion is removed and replaced. Sometimes what is missed is the water that ran off the ceiling portion into the adjacent wall causing the wall interior to remain wet for long enough for mold to blossom.
Obviously water running onto the floor from inside the wall, water stains or a wet carpet near a wall are all signs that you have a problem.
Some more subtle signs are such things as a baseboard swollen or pulling slightly away from the wall. Bubbled or cracking paint on the wall or baseboard are also signs of water damage and possible mold growth.
If you have no gutters, see if rain run-off pools next to the house where water could seep into the walls. If you have gutters, where does the run-off terminate? Does it pool against the house possibly right at the downspout?
Testing walls for elevated moisture levels, allowing for the meter possibly reading on metal inside the wall, can be quite productive for locating possible areas of water intrusion and mold growth.
Keep in mind that walls are not sealed so mold growth inside walls does not just stay there encapsulated. Air does move in and out of wall cavities, mold spores will move with the air currents. The worst place for mold to be present inside wall cavities is probably the bedroom. We spend a lot of time there and the body is supposed to be repairing itself during sleep. If you are being exposed to contaminants at that time, body repair is likely to be impaired or could even go backwards.
Particularly if you experience respiratory symptoms in your home or if you wake up with stuffy nose or other respiratory symptoms, it could be beneficial to determine if you have hidden contamination that could be the source of your malady.